Conventional steam reforming reaction for producing hydrogen requires substantial amount of energy supply from an external heating system and an additional purification facility, such as pressure swinging absorber (PSA) or cryogenic purifier, to attain the desired purity of 95 to 99.995%. Since the external facilities generally occupy a larger share of the capital investment and the plant space, a membrane assisted steam reformer is incorporated to provide simplification in the hydrogen purification system. Lately, additional development focuses on in-situ heating by conventional combustion of fuel or spent gases of the reformer inside the reformer to provide the energy required for the endothermic steam reforming reaction disclosed on US patent application publication Nos. US2003/0068260 A1 and US2003/0068269 A1. In U.S. Pat. No. 5,861,137, a small burner is provided to burn the fuel or vent product gases to provide the needed thermal energy; however, it produces dangerous open flame and NOx polluting product. In US patent application publication No. US2003/0068629 A1, the flameless burning is provided by preheating the fuel and air to a temperature above the autoignition temperature of the mixture. Apparently, the foresaid developments still suffer severe shortcomings including the hazard of vapor phase combustion and the generation of noxious pollutants, nitrogen oxides, NOx from the vapor phase air combustion.
In order to overcome the foresaid drawbacks, the present invention provides a process and a shell and tube reactor module to produce hydrogen with high purity (99.99%). Furthermore, the present invention provides a process and a shell and tube reactor module having a combustion section which can rapidly reach to a high temperature sufficient to initiate an endothermic steam reforming reaction in a very short time.